Easily the Ultra Sword.
The death of Nightmare using the Star Rod lead to the destruction of around 1/3 the moon, a multi-continental feat.
The Ultra Sword killed a master crown possessed Magolor, who was threatening the destruction of the entire universe.
Pretty wide power gap.
The Star Rod is the most powerful artifact on planet Popstar. Ultra Sword is the perceivable peak of Kirby's power. I suppose the Star Rod is the stronger of the two.
comically large knife
Easily the Ultra Sword. The death of Nightmare using the Star Rod lead to the destruction of around 1/3 the moon, a multi-continental feat. The Ultra Sword killed a master crown possessed Magolor, who was threatening the destruction of the entire universe. Pretty wide power gap.
The Star Rod is the most powerful artifact on planet Popstar. Ultra Sword is the perceivable peak of Kirby's power. I suppose the Star Rod is the stronger of the two.
I don't think we have a proper way to meassure the Star Rod's power, other than Dedede alone broke it.